1. Field of the Invention
The invention relates to a device for hydromechanical descaling of continuous cast slab and/or hot-rolled metal strip, especially of steel, comprising water spray nozzles, correlated respectively with one strip side and arranged successively in the transport direction of the strip as well as laterally adjacently to one another, for spraying high-pressure water jets onto the two strip surfaces, wherein the rows of spray nozzles arranged on the top side of the strip together with catch troughs are arranged to be pivotable about an axis, respectively, and are vertically adjustable relative to the top side of the strip according to a signal of a measuring device.
2. Description of the Related Art
When hot-rolling slab and strips, the scale must be removed before rolling in order to achieve a good quality surface. It is known to perform such descaling by high-pressure water ejected from nozzle devices with pressures of up to 1,000 bar. It is known to arrange stationary upper and lower nozzles with relatively large spacing to the strip surface so that strip thickness variations and wave-shaped strip irregularities can be compensated. A disadvantage is that on the xe2x80x9cwave peakxe2x80x9d the descaling parameters (impact, spacing, coverage etc.) are optimal, but are unsatisfactory on the xe2x80x9cflatxe2x80x9d strip.
A known descaling device for descaling with high pressure water is disclosed in patent document DE 43 28 303 A1. In the nozzle device known from this patent document a row of rotating nozzle heads, having respectively four nozzles distributed about the circumference for spraying high-pressure water, is mounted on a beam, which is stationarily arranged transverse to the movement direction of the rolling stock moved underneath it at such a spacing that the curved portions and irregularities of the rolling stock guided along the spray device will not cause a collision. Accordingly, this spacing is comparatively large. This reduces the jet pressure of the high-pressure water on the rolling stock, and this can only be compensated by increasing the water pressure or the amount of water thus requiring a great energy expenditure.
In order to avoid these disadvantages, a device for descaling of semi-finished products has been proposed with the German patent application P 198 17 002.5, which was not published at the time of filing the priority application of the instant application. This device applies a fluid at high pressure onto the surface of the semi-finished product being moved relative to the spray device and comprises also, if needed, a device for removing the scale. With this device a more uniform descaling impact pressure, the so-called impact, and thus a more uniform descaling across the strip width and length can be achieved in comparison to conventional devices. For this purpose, means are provided for a direct detection of the strip profile, wherein, as a function thereof, the spray device and/or the scale removal device can be individually vertically adjusted, respectively.
The patent document EP 0 360 480 B1 describes a descaling device for a material strip with a device for bending the strip at one point by means of at least one bending roll and a water spraying device which sprays the water onto a descaling location which is spaced slightly from-the bending location in the strip transport direction. By bending the strip, the scale is supposed to break off, respectively, become detached from the surface of the strip so that the descaling action can be performed at a comparatively reduced water pressure.
The document WO 97/11797 describes a device for descaling semi-finished products. In this arrangement, a nozzle device with a vertical component is arranged above the surface of the semi-finished product and is moveable by means of a drive. A travel transducer for detecting the spacing of the nozzle arrangement from the surface is provided. Moreover, a control device for acting on the drive as a function of an output signal of the travel transducer is provided for maintaining the spacing at a constant value.
The patent document DE 29 22 701 C2 discloses a device for descaling hot-rolled metal strip in a strip mill train in which the strip, after descaling, is cold-rolled in a downstream rolling stand. Nozzle rows for spraying descaling agent are provided which are correlated with one strip side and arranged successively in the transport direction of the strip but staggered relative to one another. Each of the nozzle rows parallel to the plane of the strip is pivotable by means of a holder about an axis, that is perpendicular to the strip plane and to the longitudinal center axis of the strip, by an adjustable angle xcex1 relative to the longitudinal center axis of the strip and is secured at a slant angle, the so-called jet impact angle xcex2, of the nozzle axes to the strip surface of less than 90xc2x0. The holder of a nozzle bearing block supporting the nozzle row has a pivot device for changing the slant angle, respectively, the jet impact angle xcex2 of the nozzle axes to the strip surface while at the same time maintaining the point of the interception of the nozzle axes with the strip plane.
It is an object of the present invention to provide a device for hydromechanical descaling of the aforementioned kind, which, in comparison to the prior art, is developed to an extremely efficient functional unit and which has significant advantages in the case of a collision.
In accordance with the present invention, this is achieved in that the water catch troughs are pivotable about a pivot point counter to the transport direction of the strip and independent of the water spray nozzles and are vertically adjustable relative to the metal strip and automatically yielding, and in that the spray beams receiving the spray nozzle rows at the top side of the metal strip are freely pivotable by means of a lever arm about the pivot point of the water catch troughs and are thus, within limits, vertically adjustable as well as automatically yielding. With these measures, the collision risk with the metal strip is significantly reduced.
According to one embodiment of the invention, it is proposed that the spray nozzle rows, together with the spray beams receiving them as well as the catch troughs interacting therewith, at the top side of the metal strip are positioned within a hood receiving the spray nozzle rows and the spray beams with their pivot axes, wherein the hood is supported by four lifting cylinders arranged on the corners of the hood and correlated with the upper drive rolls.
With the inventive configuration of the descaling device an extremely compact design is realized wherein the hood receiving the spray beams and the catch troughs can be immediately lifted, for example, in the case of an upwardly bent leading strip portion, with the aid of the four lifting cylinders arranged on the corners, and repair work and/or servicing or maintenance is facilitated.